The present embodiments relate to a coil for a magnetic resonance device.
Magnetic resonance devices with cylindrical magnets may include a number of cylindrical superconducting coils, which are used for magnetic field generation or field homogenization or screening. The cylindrical superconducting coils may be, for example, primary coils or shim coils. The cylindrical superconducting coils are formed for cylindrical magnets by a cylindrical coil insulating frame that may be made of metal. Since only by using a metal coil insulating frame can it be ensured that only minimal changes occur to the geometry of the coil through shrinkage of the coil insulating frame when the coil is cooled down to reach its superconducting state. One or more coil grooves are provided on the coil insulating frame, which run around its outer side and open radially outwards. These grooves are milled into the coil insulating frame with the desired geometry. To electrically insulate the coil insulating frame from a coil conductor wound into one of these grooves, insulation is applied which acts as a lining for the groove. Subsequently, the coil conductor, which may be made from superconducting material, is wound in.
For known coils with metallic coil insulating frames, the insulation is manufactured using an insulating film that is wound as a number of layers into the groove. If this has to be manipulated further on the floor of the rectangular cross-section groove, considerable difficulties arise in covering the sides of the groove, both regarding the covering of the actual groove sides and in establishing an insulating transition between the groove edge insulation and the floor insulation. The insulation must be applied exactly since in the event of a fault it can be subjected to high voltages, which must be isolated to avoid damaging the magnet. These high voltages are in the range of several kV. The insulation must be applied without creases and air bubbles, since these types of faults can lead to reduced insulation which may be able to be punctured by voltages. The films to be used may have faults. For example, the films can have small tears or holes, which may lead to problems during operation. The films able to be used for this purpose are expensive.